1. Field of the Invention
The present invention relates to a flow channel structure, and a mixing method, an extraction method, and a reaction method for fluids.
2. Description of the Related Art
Conventionally, flow channel structures have been known as means for causing a plurality of fluids to mix and bring about interaction between these fluids. Japanese Patent Application Laid-open No. 2006-75680 provides a flow channel structure for an extraction operation which merges two fluids, thereby extracting a subject from one fluid to the other fluid as an example of the flow channel structure.
The flow channel structure described in Japanese Patent Application Laid-open No. 2006-75680 has a flow channel for merging the two fluids while two fluids are flowing, and the flow channel is configured to merge the two fluids on a plurality of stages. Specifically, the flow channel structure is formed by horizontally piling and joining a top substrate having a first channel formed on a bottom surface and a bottom substrate having a second channel formed on a top surface. The first channel extends meanderingly on the bottom surface of the top substrate. The second channel includes a single inlet path formed on the top surface of the bottom substrate and a plurality of branch paths branching from the inlet path. Each of the branch paths vertically overlaps each of portions spaced apart along a direction in which the meandering first channel extends while the top substrate and the bottom substrate are vertically piled. Downward openings of portions which are out of the first channel, and do not overlap each of the branch paths of the second channel are sealed by the top surface of the bottom substrate, and upward openings of portions which are out of the second channel, and do not overlap the first channel are sealed by the bottom surface of the top substrate. A flow channel in which the first channel and corresponding branch paths of the second channel merge with each other at the respective portions spaced apart along the direction in which the first channel extends is formed in the flow channel structure in this way. A first fluid is caused to flow through the first channel, and a second fluid is caused to flow through the second channel. Both of the fluids merge with each other while forming an interface therebetween at each of the portions where the first channel and the branch path of the second channel overlap.
However, the first fluid flowing through the first channel and the second fluid flowing through the second channel only come in contact with each other via the interface at the portions where both of the fluids merge with each other in the above-mentioned conventional flow channel structure, and promotion of the mixture of both of the fluids is difficult, and mixture of different types of the second fluid on each of stages of mixture of the second fluid with the first fluid and individual control of flow quantities of the second fluid mixed with the first fluid on each of the mixture stages are difficult. Reasons for them are as mentioned below.
Both channels extend in parallel with each other at each of the portions where the first channel and each of the branch paths of the second channel overlap in the above-mentioned flow channel structure. As a result, the first fluid and the second fluid form the interface therebetween, and merge while flowing in parallel when both of them merge with each other at each of these portions of both of the channels. As a result, both of the fluids merge, but are not stirred, and flow downstream while maintaining the parallel state forming the interface therebetween, and the mixture of both of them is not promoted. Moreover, each of the branch paths branching from the single inlet path of the second channel overlaps and merges with each of the portions of the first channel in the above-mentioned flow channel structure, and the same type of the second fluid distributed via the inlet path of the second channel to each of the branch paths thus merges from each of the branch paths with the first fluid in the first channel. As a result, different types of second fluid from each of the branch paths cannot be merged and mixed with the first fluid in the first channel. Moreover, the flow quantity ratio of the second fluid distributed from the inlet path of the second channel to each of the branch paths is determined constant according to a channel shape thereof, and the flow quantity of the second fluid cannot be individually manipulated for each of the branch paths. As a result, the flow quantities of the second fluid to be mixed cannot be controlled at the respective stages where the first fluid in the first channel from the respective branch paths is mixed with the second fluid.